First connect red cable to the positive terminal of your C300’s dead battery, then to the positive terminal of donor battery. Next connect black cable to the negative terminal of donor battery, then to the bare metal in the engine bay of your C300. Start the donor vehicle and then your C300. Remove the cables in reverse order. Initially the cooling fan was coming on when the ignition switch was turned to start. Some fiddling about with the ecu and sam and copious amounts of electrical contact spray sorted the cooling fan. I am now left with the car not cranking. I have checked the starting relay and it is working as it should. The starting fuse is 20amp and is not blown. 4813 posts · Joined 2008. #4 · Apr 26, 2020. be aware that MB (at least my 97 E420 and 97 SL500) manual states that leaving a key in the ignition, even in the off position will cause the battery to drain prematurely. As long as it detects a key, the car won't go into full sleep mode. So.. while your solution lets you start the car, you may 8 posts · Joined 2017. #1 · Dec 7, 2017. My 2009 ML500 W164 has a dead or dodgy ignition switch module that I now have to remove. Has anyone removed one on a right hand drive model? The left hand drive models are easy as you go in via the centre consul, but I can't find any videos or instructions to get to the unit on a right hand drive model. Well, for those of us who have had the radio not work through the ignition switch (meaning you had to turn it on and off with the radio switch and not the ignition switch), I found a solution! Replace the OEM radio! I transferred my lifetime Sirius account to a new Alpine head unit and the local shop hooked it up through the Bose amplifier and A problem that Mercedes-Benz owners may face is the key no longer turns in the ignition. This issue is often caused either by a defective key, bad shifter module, a failed Electronic Ignition Switch (EIS) also known as the EIS-EZS or a bad steering lock module (ESL). This problem can affect various Mercedes-Benz models including E-Class, S I was able to install the ignition switch lock cylinder on my 2004 Mercedes 230 slk and the key turned and car started..I was happy with the results. When I removed the key and put it back in the key will not turn. Same orginial problem occurred with the new cylinder. I have reordered a new cylinder. Any idea on what is wrong Welwyn Merx Limited is a family run business with genuine passion, dedication and 25 years of experience dealing with Mercedes-Benz and AMG passenger cars. Tel: 01707 395999 www.welwynmerx.uk. Forums. Technical. Electrics, Vacuum, Ignition and ECU. Hi everyone. I have an issue with my slk 350. R171 2006. Started the car today for the first time a9GumV.